20724 has 24 divisors (see below), whose sum is σ = 53088. Its totient is φ = 6240.

The previous prime is 20719. The next prime is 20731. The reversal of 20724 is 42702.

It is a nialpdrome in base 12.

It is a congruent number.

It is an unprimeable number.

20724 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 54 + ... + 210.

It is an arithmetic number, because the mean of its divisors is an integer number (2212).

2²⁰⁷²⁴ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20724, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26544).

20724 is an abundant number, since it is smaller than the sum of its proper divisors (32364).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20724 is a wasteful number, since it uses less digits than its factorization.

20724 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 175 (or 173 counting only the distinct ones).

The product of its (nonzero) digits is 112, while the sum is 15.

The square root of 20724 is about 143.9583273034. The cubic root of 20724 is about 27.4678411957.

It can be divided in two parts, 207 and 24, that added together give a triangular number (231 = T₂₁).

The spelling of 20724 in words is "twenty thousand, seven hundred twenty-four", and thus it is an iban number.